The objectives and work scope of the period June 1975 - June 1976 include: the completion of testing of sera (approximately 30,000) collected at Parris Island, South Carolina, for metabolic inhibition antibody against Mycoplasma pneumoniae; surveillance at batallion sick call and at the Naval Hospital, Camp Lejeune, North Carolina, of original volunteers for acute respiratory disease (paired sera and an acut throat swab specimen for M. pneumoniae will be obtained); any evidence suggesting a hypersensitivity state in OSU-1 vaccines will be sought; and routine collection of sera will be made at four month intervals in vaccinees and controls stationed at Camp Lejeune, North Carolina.